Partial asset sales will do nothing to curb New Zealand's growing debt problem, a new report by economic analysts Berl says.

The Berl report, commissioned by the Green Party and released today, says the Government's partial asset sales programme to build new assets would leave the Crown accounts ''permanently worse off''.

Government debt, the ratio of debt to assets, net worth and total assets would all be worse off after the programme was carried out, Berl found.

''The interim loss of earnings resulting from reduced dividends and the period of time before the new assets reap benefits is never recouped,'' the report said.

''Subsequently, the option of asset sales can only significantly improve the Government's accounts if a set of assumptions are adopted that are at the extreme ends of plausibility.''

The partial asset sales programme will see up to 49 per cent of four state owned energy companies and Air New Zealand sold down to private investors over the next four years. The sales are expected to net around $5b to $7b for the Government, some of which has already been tagged for re-investment in infrastructure like schools and an irrigation fund.

Berl chief economist Ganesh Nana said the loss of dividends from the companies was not compensated by a decrease in spending.

In the longer term, the new investments might perform just as well or better than the dividends from the former assets, but there was no clear evidence that would happen.

Some of the shares may also be sold overseas, guaranteeing a worsening of net external debt.